Ppb-Level 2-Butanone Gas Sensor Based on CTAB-Assisted Synthesis of Small-Size ZnSnO Nano Cube

The cubic Zn2SnO4 with different sizes is synthesized by adjusting the concentration of surfactant cetyltrimethyl ammonium bromide (CTAB) in the hydrothermal process. The structure, morphology, and specific surface area of Zn2SnO4 nanoparticles are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and so on. By adding surfactant in the synthesis process, the Zn2SnO4 material is changed into a regular cubic structure from an irregular shape. When the concentration of surfactant is further adjusted, the size of the cubic structure first decreased and then increased. The test results show that the response of the Zn2SnO4 sensor prepared with 0.5-mmol CTAB to 100-ppm 2-butanone reaches 80 at the optimal working temperature of 300 °C. Under the same test conditions, its response is 2.34, 2.58, and 4.79 times that of ZTO-0, ZTO-0.1, and ZTO-1, respectively. Compared with the ZTO-0 sensor, the response time is scaled back from 33 to 6 s, and the detection limit is cut down to 100 ppb. The exceedingly superior gas sensitivity is caused by the regular morphology and small size effect of the powder materials.